The present invention relates to methods of treating subterranean formations with treatment fluids comprising proppant aggregate suspension aids.
Subterranean wells (e.g., hydrocarbon producing wells, water producing wells, and injection wells) are often stimulated by hydraulic fracturing treatments. In hydraulic fracturing treatments, a treatment fluid is pumped into a portion of a subterranean formation at a rate and pressure such that the subterranean formation breaks down and one or more fractures are formed. Typically, particulate solids, such as graded sand, bauxite, ceramics, or even nut hulls, are suspended in a treatment fluid and then deposited in the fractures. These particulate solids, or “proppant particulates,” are generally deposited in the fracture in a concentration such that they form a tight pack of particulates, or “proppant packs,” which serve to prevent the fractures from fully closing once the hydraulic pressure is removed. By keeping the fracture from fully closing, the proppant particulates aid in forming conductive paths through which fluids may flow.
Gelled treatment fluids, because of their increased viscosity, are useful in transporting and depositing proppant particulates into subterranean fractures. Additionally, crosslinking agents are often used to further increase the viscosity and stability of gelled treatment fluids to further enhance the fluid's utility in some downhole environments.
In traditional subterranean operations, the specific gravity of individual proppant particulates is high in relation to the gelled treatment fluid in which they are suspended for transport and deposit in a fracture. Therefore, the proppant particulates tend to settle to the bottom portion of a fracture. The settling nature of traditional proppant particulates can result in complete occlusion of a portion of the fracture where no proppant particulates have collected (e.g., at the top portion of the fracture) when the fracture closes, impairing fracture conductivity and production over the life of a subterranean well.
One way to compensate for proppant particulate settling and partial fracture closure is to transport and deposit the highest possible concentration of proppant particulates into a fracture in order to decrease the likelihood of void space in the fracture. However, increasing the proppant particulate concentration in a treatment fluid generally requires a higher concentration of gelling agents and/or crosslinker within the gelled treatment fluid. As many gelling and crosslinking agents are used in a variety of fluids outside the oil and gas industry, their demand is increasing while their supply is decreasing. Therefore, the cost of gelling and crosslinking agents is increasing, and consequently, the cost of subterranean operations requiring the highest possible concentration of proppant particulates is also increasing.
The degree of success of a fracturing operation depends, at least in part, upon fracture conductivity once the fracturing operation has ceased and production commenced. Therefore, a practical method of hindering the settling rate of proppant particulates suspended in a treatment fluid in order to prevent partial fracture closure while decreasing quantity and cost of gelling and crosslinking agent may be of value to one of ordinary skill in the art.